Scientists Unearth Long Record of Past Hurricanes

Digging down in a Caribbean lagoon, researchers go back in time

Reaching down into the muck below a lagoon off Puerto Rico, two geologists at Woods Hole Oceanographic Institution reached back 5,000 years to compile the longest record of strong hurricanes in the Atlantic region.

The record showed that the dominant forces spawning heightened hurricane activity appeared to be atmospheric conditions generated by weak El Niños in the tropical Pacific and strong West African monsoons, Jeff Donnelly and Jon Woodruff reported May 24, 2007, in the journal Nature.

Somewhat to their surprise, they also found extensive periods of intense hurricanes in the past, when ocean temperatures were cooler than they are now. Today, concerns about global warming have focused public attention on warmer ocean waters as a prime suspect for increased hurricane activity.

“Warm sea surface temperatures are clearly important in fueling intense hurricanes,” Donnelly said. “Over the past several thousand years, ocean temperatures have never been as warm as they are now, so we have no analog to help predict how they will affect hurricane activity.”

“But our research demonstrates that the El Niño/Southern Oscillation and the West African monsoon are certainly important,” he said. “Understanding how they will change in a warming world could be extremely important in determining the kind of hurricane activity we will see in the future.”

Donnelly, an associate scientist at WHOI, and Woodruff, a doctoral student in the MIT/WHOI Joint Graduate Program, began reconstructing the history of Caribbean hurricanes in 2003, by driving 13-foot (4-meter) cores through the bottom of Laguna Playa Grande on Vieques, Puerto Rico. The lagoon is protected and separated from the ocean by dunes during all but the most severe tropical storms. But storm surges from intense hurricanes carry sand and bits of shells from the ocean beach over the dunes and into the lagoon, leaving telltale layers in the typically black, organic-rich silt on its bottom.

The interspersed layers of silt and sand recorded long stretches of frequent hurricane strikes punctuated by lulls that lasted many centuries. The team then compared their new hurricane record with other climate influences, such as El Niño, the periodic diminishing winds and buildup of warm waters in the eastern tropical Pacific. Other researchers have established that El Niño can stunt hurricane activity by causing strong high-altitude winds that shear the tops off hurricanes or tip them over as they form.

The researchers also examined precipitation records from Lake Ossa, Cameroon, and discovered that when monsoon rains increased, intense hurricanes occurred more often on the other side of the Atlantic. Researchers have theorized that storms over western Africa generate atmospheric waves that move into the Atlantic and provide “seedlings” for hurricane development.

“If we have few El Niño events and a strong West African monsoon, combined with exceedingly high sea surface temperatures, we could experience an active hurricane period that is unprecedented in the last 5,000 years,” Donnelly said. “Conversely, if we have more steady-state El Niño conditions, it may reduce—but not stop—intense hurricane activity in a warmer world.”

The research was funded by the National Science Foundation, the Risk Prediction Initiative, the National Geographic Society, the WHOI Coastal Ocean Institute, and the Andrew W. Mellon Foundation.

Laguna Playa Grande (left) sits behind a vegetation-covered barrier beach that is as much as 260 feet (80 meters) wide and 7 to 10 feet (2 to 3 meters) high. Laguna Playa Grande (left) sits behind a vegetation-covered barrier beach that is as much as 260 feet (80 meters) wide and 7 to 10 feet (2 to 3 meters) high. Surges from intense storms carry sand from the ocean beach over the dunes and into the lagoon. Such "over-topping" events leave distinctive layers of coarse-grained sands and bits of shell interspersed between the organic-rich silt usually found in lagoon sediments.

Graduate student Jonathan Woodruff of the WHOI Geology and Geophysics Department works to sink a coring tube into the sediments beneath Laguna Playa Grande. (Photo by Erin Bryant)

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Simon Thorrold, Ocean Ecologist

Simon Thorrold is an ocean ecologist at Woods Hole Oceanographic Institution. He uses techniques that span isotope geochemistry, next generation DNA sequencing, and satellite tagging to study the ecology of a wide variety of ocean species. He recently discovered that blue sharks use warm water ocean tunnels, or eddies, to dive to the ocean twilight zone, where they forage in nutrient-rich waters hundreds of meters down. Born in New Zealand, Simon received his B.S. from the University of Auckland, and Ph.D. from James Cook University, North Queensland, Australia. With much of his work in the South Pacific and Caribbean, Simon has been on many cruises, logging 1,000 hours of scuba diving and 800 hours in tropical environs. He has been a scientist at Woods Hole Oceanographic Institution since 2001.

Gregory Skomal, Shark Biologist

Dr. Gregory Skomal is an accomplished marine biologist, underwater explorer, photographer, and author. He has been a fisheries scientist with the Massachusetts Division of Marine Fisheries since 1987 and currently heads up the Massachusetts Shark Research Program. He is also adjunct faculty at the University of Massachusetts School for Marine Science and Technology and an adjunct scientist at the Woods Hole Oceanographic Institution (WHOI). He holds a master’s degree from the University of Rhode Island and a Ph.D. from Boston University. For more than 30 years, Greg has been actively involved in the study of life history, ecology, and physiology of sharks. His shark research has spanned the globe from the frigid waters of the Arctic Circle to coral reefs in the tropical Central Pacific. Much of his current research centers on the use of acoustic telemetry and satellite-based tagging technology to study the ecology and behavior of sharks. Greg has been an avid SCUBA diver and underwater photographer since 1978. He has written dozens of scientific research papers and has appeared in a number of film and television documentaries, including programs for National Geographic, Discovery Channel, BBC, and numerous television networks. His most recent book, The Shark Handbook, is a must buy for all shark enthusiasts. He is a Boston Sea Rover and a member of The Explorers Club; his home and laboratory are on the south coast of Massachusetts.

Robert Ballard, Ocean Explorer

Robert Ballard, Ocean Explorer

Robert D. Ballard is Founder and President of the Ocean Exploration Trust; Director of the Center for Ocean Exploration and Professor of Oceanography at the University of Rhode Island Graduate School of Oceanography. He is an Explorer-At-Large at the National Geographic Society, Commissioner for the U.S. Commission on Ocean Policy, and a Research Scholar at the Woods Hole Oceanographic Institution. He served in the U.S. Navy for more than 30 years and continues to work with the Office of Naval Research. A pioneer in the development of deep-sea submersibles and remotely operated vehicle systems, he has taken part in more than 155 deep-sea expeditions. In 1985, he discovered the RMS Titanic, and has succeeded in tracking down numerous other significant shipwrecks, including the German battleship Bismarck, the lost fleet of Guadalcanal, the U.S. aircraft carrier Yorktown, and John F. Kennedy’s boat, PT-109. He has also discovered hydrothermal vents and “black smokers” in the Galapagos Rift and East Pacific Rise in 1977 and 1979. The author of numerous books, scientific papers, and articles, he has been featured in several National Geographic television programs, including “Secrets of the Titanic” a five-part mini-series, “Alien Deep with Bob Ballard.” and, in 2019, “Expedition Amelia.” He was a special advisor to Steve Spielberg on the futuristic television show seaQuest DSV. His honors include 22 Honorary Doctorates, National Geographic’s highest award, the Hubbard Medal, and a National Endowment for the Humanities Medal. He was elected a Fellow of the American Academy of Arts and Sciences in 2014.

Timothy Shank, Deep-Sea Biologist

Tim Shank, Deep-Sea Biologist

Timothy Shank is a deep-sea biologist, Associate Scientist in the Biology Department, and former Director of the Ocean Exploration Institute at the Woods Hole Oceanographic Institution. He is known for his research on the ecology and evolution of fauna in deep-ocean hydrothermal, seamount, canyon and deep trench systems. He has conducted more than 60 scientific expeditions in the Arctic, Atlantic, Pacific, and Indian Oceans. Tim has completed more than 50 dives in the human operated submersible Alvin, and more than 100 dives with autonomous underwater and remotely-operated vehicles, including the first use of a hybrid ROV (Nereus) in the ocean’s deepest trenches. He is the author of the award-winning, best-selling book “Discovering the Deep.”

Sunita Williams, NASA Astronaut

NASA Astronaut Sunita L. Williams

Sunita L. Williams (Suni) was selected as an astronaut by NASA in 1998 and is a veteran of two space missions Expeditions 14/15 and 32/33. She is currently training for the first post-certification mission of Boeing’s Starliner spacecraft – the second crewed flight for that vehicle – and her third long duration mission aboard the International Space Station. Williams and her crewmates are working closely with Boeing to develop their new spacecraft systems, which will provide roundtrip crew transportation services to the International Space Station and, along with SpaceX’s CrewDragon, return the ability to launch humans into space from United States soil.

Kirstin Meyer-Kaiser, WHOI Biologist

Kirstin Meyer-Kaiser, WHOI Biologist

Kirstin Meyer-Kaiser is an Assistant Scientist in the Biology Department at Woods Hole Oceanographic Institution. Her research explores how the larvae of seafloor invertebrates such as anemones and sea stars disperse to isolated, island-like habitats, how larvae settle and colonize new sites, and how their communities change over time. Kirstin is currently Principal Investigator for an interdisciplinary project on shipwrecks in Stellwagen National Marine Sanctuary, including the steamship Portland, often termed “New England’s Titanic.” This project uses cutting-edge technology to construct 3D photogrammetric models of the Portland and other wrecks for archaeological and biological research and resource management. Kirstin also has ongoing projects in the Arctic and on coral reefs in Palau. Her work frequently takes her underwater using remotely operated vehicles and SCUBA and carries her to the far corners of the world.